What Monte did say was "My decision is one based on differences of opinion with the company." The question here then is a difference of opinion on what?
Many people are assuming that it was a difference of opinion on game mechanics, etc. Personally, I think that's a stretch. He further went to say that "my differences were not with my fellow designers, Rob Schwalb and Bruce Cordell..." He even went so far as to make a clarification that not mentioning Mike Mearls was not an "indictment" (I'm not going to link because it's all on the same site). So we can safely assume it wasn't a personality issue - it was a company issue. That means it could be any number of things, but it doesn't necessarily mean it was anything related to game mechanics, design elements, etc.. of 5e. It simply could have been salary issues, intellectual property issues, or any number of business oriented issues.
The important thing to keep in mind is that we don't know for sure what it was that made him leave, and more important speculation about that is really pointless. It only causes people to get defensive, aggressive, or just misinformed. The best thing we can as people who love D&D is support the current team in their development of the game through positive conversations in forums like this (and positive can still include a critique), and playtesting.
Many people are assuming that it was a difference of opinion on game mechanics, etc. Personally, I think that's a stretch. He further went to say that "my differences were not with my fellow designers, Rob Schwalb and Bruce Cordell..." He even went so far as to make a clarification that not mentioning Mike Mearls was not an "indictment" (I'm not going to link because it's all on the same site). So we can safely assume it wasn't a personality issue - it was a company issue. That means it could be any number of things, but it doesn't necessarily mean it was anything related to game mechanics, design elements, etc.. of 5e. It simply could have been salary issues, intellectual property issues, or any number of business oriented issues.
The important thing to keep in mind is that we don't know for sure what it was that made him leave, and more important speculation about that is really pointless. It only causes people to get defensive, aggressive, or just misinformed. The best thing we can as people who love D&D is support the current team in their development of the game through positive conversations in forums like this (and positive can still include a critique), and playtesting.